‘From the back I thought it was Prince William,’ said one royal subject.

Someone grab a crown, quick! Prince Harry showed off a startlingly sparse head of hair at the London premiere of WW2 flick Dunkirk on July 13.

“From the back I thought it was Prince William!” said one royal subject at the event. Indeed, Harry’s 35-year-old brother often quips about being follicle-challenged, but Harry, 32, seemed to have dodged the balding bullet — passed down from his maternal grandfather — but apparently not.

“It was pretty noticeable in person and you can tell he’s just going to lose more hair,” added the spy. “Maybe that’s why he’s growing a beard — to prove he still can!”